High-voltage switchgear cabinets are crucial electrical equipment in power systems, primarily used for the distribution, measurement, protection, control, and regulation of electrical energy within voltage ranges of 3.6KV to 550KV. These cabinets are assemblies of primary and secondary devices, including circuit breakers, disconnectors, transformers, and measurement, protection, and control equipment, all enclosed within a metal cabinet for safety and organization.
Types and Structures:
High-voltage switchgear cabinets can be classified based on various criteria:
- Structure: They can be either open or enclosed. Open-type cabinets have exposed high-voltage busbars and unseparated components, while enclosed types have isolated components for enhanced safety, suitable for harsh environments. Enclosed cabinets further include metal-enclosed, metal-clad, metal-enclosed box-type, and SF6 gas-insulated switchgear.
- Installation Method: Fixed or withdrawable (handcart type). Fixed cabinets have all electrical equipment permanently mounted, while withdrawable cabinets allow the circuit breaker and its operating mechanism to be moved in and out on a trolley for ease of maintenance.
- Busbar Configuration: Single-bus or double-bus systems, with single-bus systems commonly used in distributions below 35KV.
Key Features and Functions:
One of the most significant features of high-voltage switchgear cabinets is their “five-prevention” interlocking mechanism, which ensures operational safety:
- Prevention of Incorrect Circuit Breaker Operation: Circuit breakers can only be operated when the handcart is in the working or test position.
- Prevention of Live Grounding Switch Operation: Grounding switches can only be closed when the circuit breaker handcart is in the test position.
- Prevention of Access to Live Compartments: Rear doors can only be opened when the grounding switch is closed or the high voltage is off.
- Prevention of Moving Loaded Circuit Breaker Handcarts: Handcarts can only be moved when the circuit breaker is open.
- Prevention of Energizing with Grounding Switch Closed: The circuit breaker handcart can only be pushed into the working position when the grounding switch is open.
Installation and Maintenance:
Proper installation and regular maintenance are vital for the reliable operation of high-voltage switchgear cabinets. Before installation, the product manual should be carefully read, and installation should adhere to the specified requirements, including necessary commissioning. Regular inspections and maintenance ensure the cabinet’s normal operation and prompt detection and repair of faults. These activities should only be performed by qualified professionals to guarantee safety and reliability.
Applications:
High-voltage switchgear cabinets are widely used in power systems, petrochemicals, metallurgy, coal mining, and other industries, providing critical safety and stability for electrical equipment operations, especially in harsh environments.
